Piedmont Lithium Ltd (ASX:PLL) (NASDAQ: PLLL) has produced consistent high-grade spodumene concentrates with low iron content in tests of samples from its lithium project in North Carolina, USA.
The bench-scale metallurgical tests included spodumene flotation optimization, magnetic separation to remove iron from spodumene concentrate and heavy liquid separation (HLS).
Piedmont partnered with North Carolina State University’s Minerals Research Laboratory (MRL) to complete the tests.
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The company is developing a vertically integrated model for its Piedmont Lithium Project in the world-class Carolina Tin-Spodumene Belt.
Spodumene direct flotation tests followed by magnetic separation tests were conducted on four samples of Piedmont ore.
Encouraging flotation results
Flotation results showed that spodumene concentrates with grades of greater than 6.0% lithium oxide were achievable with two-stage magnetic separation tests reducing iron content to less than 1.0%.
It was also demonstrated that the ultimate tailings streams of the bench-scale flowsheet had low lithium oxide losses.
These results will underpin the spodumene concentrator process design within a scoping study for the project, which is expected later this quarter.
The bench-scale results will also be used to guide future pilot-scale test work programs.
Heavy liquid separation results
MRL conducted HLS tests on an ore sample to evaluate a potential dense medium separation (DMS) circuit for upgrading spodumene prior to flotation.
Results showed that the potential DMS circuit may produce a final spodumene concentrate with a lithium oxide content of 5-6% at a specific gravity cut of 2.95.
In addition, the DMS may exclude a portion of the raw feed to final tailings with low lithium oxide losses at a specific gravity cut of 2.70.
Finally, the portion of the feed in the specific gravity range of -2.95+2.70 considered as middlings may produce a pre-concentrated feed to the flotation circuit.
DMS a potential circuit
HLS summary data showed that DMS may be a potential circuit within Piedmont’s planned spodumene concentrator.
The company will undertake trade-off studies and further tests to evaluate the potential of DMS as a pre-concentration or final product process circuit design.
These studies will be included in a planned update to the scoping study, which is expected to be completed by the end of the year.
The completed test work confirms the interim flotation and magnetic separation results achieved earlier this year with additional tests on four composited samples from multiple exploration corridors within the core property.
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MRL is now concluding bench-scale by-products production tests from tailings samples with final results expected in the coming weeks.
The tests include evaluation for the potential of saleable quartz, feldspar, and mica products.
Piedmont expects to produce a minimum of 100-kilogram sample of spodumene concentrate for bench-scale lithium chemical conversion test work.
This test work is expected to start in the second half of 2018 while pilot plant-scale concentration test work using a bulk sample is also scheduled.
Initial ore sorting test work is scheduled for early August using Steinert ore sorting technology.